ANU astrophysicist and cosmologist Dr Brad Tucker says scientists can know up to "100 years in advance" if an asteroid is on a collision course with Earth.
"That's the good thing, these larger ones we know, we know most of them, where they are," he told Sky News Australia.
"The only one that may come close – close being within 20 million kilometres – wouldn't be until the end, I think about 2090, maybe 2100, that's the only one we ever look at."
Dr Tucker said it is likely this asteroid will not come close to the Earth when it passes.
He said the smaller asteroids of 50 to 100 metres are of more concern as scientists only know the location of a few of them, and the NASA DART mission will help to track more.
"This whole DART mission is part of a suite of projects to better prepare for this threat," he said.
"So not just can we defend against it, but can we find them, can we catalogue them, can we track them, so we know where they are."